PRDM5 Expression and Essential Role After Acute Spinal Cord Injury in Adult Rat

PR (PRDI-BF1 and RIZ) domain proteins (PRDM) are a subfamily of the kruppel-like zinc finger gene products that modulate cellular processes such as differentiation, cell growth and apoptosis. PRDM5 is a recently identified family member that functions as a transcriptional repressor and behaves as a putative tumor suppressor in different types of cancer. However, the expression and function of PRDM5 in spinal cord injury (SCI) are still unknown. In the present study, we have performed an acute SCI model in adult rats and investigated the dynamic changes of PRDM5 expression in the spinal cord. We found that PRDM5 protein levels gradually increased, reaching a peak at day 5 and then gradually declined to a normal level at day 14 after SCI with Western blot analysis. Double immunofluorescence staining showed that PRDM5 immunoreactivity was found in neurons, astrocytes and microglia. However, the expression of PRDM5 was increased predominantly in neurons. Additionally, colocalization of PRDM5/active caspase-3 was been respectively detected in neurons. In vitro, we found that depletion of PRDM5 by short interfering RNA, obviously decreases neuronal apoptosis. In summary, this is the first description of PRDM5 expression in SCI. Our results suggested that PRDM5 might play crucial roles in CNS pathophysiology after SCI and this research will provide new drug targets for clinical treatment of SCI.